Tropical Weather Update - 60% Chance of Development Over 7 Days

July 31, 2024

The National Hurricane Center is still watching a tropical wave as it moves west across the Atlantic. Currently located over the Leeward Islands, the NHC gives this wave a 60% chance of development over the next 7 days. Conditions have just been marginal enough for this wave to remain a player but the environment is expected to improve as it continues west-northwest.

You can get an idea of the possible future of this system by looking at the orange triangle shape and for now that is all you really need to know so you can stop reading here if you want. I'll tell you what the consensus is and then I'll tell you my thoughts. The current consensus is to favor the Euro (which shows development along the East Coast) because it has been very consistent and picked up on the chance of development earlier. You can see this in that most of the triangle stays to the right and out of the Gulf. I am a bit leary of trusting the Euro this early and I'll explain why after I give you a few more details on what the models are showing.

Throughout the history of this system the Euro (both the operational model and the ensembles) have been much more bullish on development than the GFS suite. The Euro picked up on development first, with the GFS only showing development many days later. The Euro, again both the operational model and a majority of the ensembles, has also been consistent at developing a storm near the Bahamas with varying tracks along the East Coast. The GFS operational model on the other hand, which again jumped on board a bit later than the Euro, has been favoring solutions that wait until the wave is in the Gulf before development occurs. The GFS ensembles typically have only had a minority of members showing development with forecast tracks waffling between the Gulf and East Coast and sometimes split between the two. For what it's worth, the Canadian model has favored Gulf development, but it has had some solutions similar to the Euro. But the overall consensus, weighted by the Euro and its 51 ensemble members, favors an East Coast solution. I will say also that the details behind why the different models are showing different solutions favors the Euro as well, people smarter than me see the Euro's solution as the more logical one, so it's not just that they're jumping on board because of a strong model consensus.

Now my thoughts. I think I have explained before that until a center of circulation has formed the models are just sort of guessing at when and where development may occur. When and where the storm actually forms can make a huge difference as to its eventual track and intensity. So there is that piece that is always in play. Also, the Euro (and its ensembles) were wrong with Beryl's track for a long time, it wasn't until just a few days beforehand that they started to show a landfall along the upper Texas coast. It was locked into a more southerly track with Beryl into Mexico and southern Texas. It is a bit counter intuitive, but the lack of a diverse set of outcomes from an ensemble suite (underdispersion) is a bad thing. We know forecasts are uncertain, and when a 51 member model fails to show uncertainty, especially when we know the forecast is uncertain as we did with Beryl and as we do now, that is indicating some kind of bias towards one particular solution. Biases can keep a model from showing a range of possible outcomes or cause a model to favor one influencing factor more so than it should. My concern is that we may be seeing a bias again in this case. It's not that I think the Euro is forecasting the future environment incorrectly, I have no basis for thinking that. I'm just a bit concerned with the overconfidence this early, especially with the Euro's history with Beryl. The Euro's forecast of East Coast development may very well be correct, as I mentioned many people are leaning this way, but I'm not going to feel comfortable about that until other models start jumping on board, until we have an overall consensus. We should have better data in a few days when this starts to tighten up and/or when it's designated an invest and the suite of hurricane models start to run.

So that's a long read and hopefully it's helpful. I think we'll start to have a better idea of where this system may go over the weekend. Hopefully this stays out of the Gulf but it's too early to write that off.

Have a good rest of the week.

Chris

Activity in the Tropics Expected to Increase Soon

July 24, 2024

A short update this morning to let you know that there are signs that we are getting close to an increase in activity in the tropics. First, there is no development expected in the Atlantic over the next 7 days so certainly no concerns. However, looking at the Global Tropical Hazards Outlook that was issued yesterday, you can see that there is a 20% chance of development indicated for weeks 2 and 3 (July 31 to August 13). This forecast is based on the expectation that environmental conditions for tropical cyclones will gradually improve in the coming days and because signals in the ensemble models, particularly the Euro, are showing an increasing probably of storm development in the areas indicated. Also, the Eastern Pacific is showing signs of possible activity in the coming week and that often portends activity in the Atlantic as you all know.

Atlantic 7-Day Outlook

Global Tropical Hazards Outlook

Once the current quiet period comes to an end we will likely not see much of a lull in activity until later in the fall. In fact, the signal is so strong that the long term precipitation outlook for August through October is for above average rainfall amounts in the Southeast driven by the expected high level of tropical cyclone activity.

Here in the southeast expect temps to get back to normal or a bit above normal as we end July and head into the first week of August. Rain chances are expected to stay a bit above normal as well.

Have a good rest of the week and a good weekend.

Chris

Nothing Doing in the Tropics - No Activity Expected Until August

July 18, 2024

It's been two weeks since my last tropical weather update when Beryl was still headed for Texas. After its landfall the tropics have been quiet. Low activity is not unusual this time of year as strong easterly winds blow dusty dry air off of the Sahara Desert creating a hostile environment for tropical cyclones across most of the Atlantic Basin. This is expected to continue for the foreseeable future (2-3 weeks, maybe a little longer) but once we get into August those winds calm and conditions improve. There's always a small chance of something popping up closer to the coast somewhere but right now no tropical cyclone activity is expected at least for a few more weeks. There's a small chance we may see a disturbance develop in the eastern Gulf next week from a weak tropical wave but I don't think it'll be anything more than a loosely organized group of storms and showers if even that.

To keep us all honest, I want to remind everyone that a high level of activity is still expected for the remainder of the season. In fact, on July 9th Colorado State University increased their forecast numbers for the remainder of the season. They are now forecasting 25 named storms, 12 hurricanes, and 6 major hurricanes (up from 23/11/5 respectively on June 11th). This includes the 3 named storms we've already had so they're expecting 22 more from here on out. In past hyperactive seasons their numbers have sometimes been conservative, so we may see even more than that. Don't let your guard down.

That's it for today. In the short term we should see some slightly cooler but wetter than normal weather followed by the return of near seasonally normal or slightly above normal temps from the last week of July into August. Rain chances look to stay slightly above normal for a while as well.

Once the development chance looks like it's starting to increase I'll send out another update.

Chris

Update on Beryl and Invest 96L, Quiet Period Coming Soon

July 3, 2024

Several pieces of good news today I think. First, confidence is fairly high that Beryl will not be a threat to the northern Gulf of Mexico but it is possible that there could be some impacts to the lower or central Texas coast. The official forecast is below. After peaking as a 165 mph category 5 storm yesterday, Beryl has finally weakened some but is still a 145 mph category 4 storm. It is expected to bring significant impacts to Jamaica within the next few hours and then to the Cayman Islands later today and overnight. The storm is expected to continue to weaken but will still be a category 2 hurricane when it makes landfall somewhere on the Yucatan Peninsula on Friday. The NHC has Beryl weakening to tropical storm strength after landfall but then restrengthening to a category 1 hurricane in the Gulf before making another landfall along the coast of Mexico or Texas Sunday or Monday.

There is still some uncertainty regarding the strength of the storm and track in the Gulf. The best resource for details on this is the Tropical Tidbits video I've linked below, but briefly if Beryl doesn't weaken as much as expected and/or traverses the narrow northern portion of the Yucatan there is the possibility of stronger storm that tracks farther north along the Texas coast whereas the opposite situation would lead to a weaker storm that stays more to the south. Again, if you missed it, the good news is that us along the northern Gulf are very likely in the clear. One impact we will see, however, is that large swells from Beryl are expected to cause dangerous rip currents along the beaches starting as soon as tomorrow and over the weekend. By the way, Beryl set a record not only by becoming the earliest category 5 hurricane but is also the strongest July hurricane on record and the earliest storm (by over a month...) with 165 mph winds!

Tropical Tidbits video from Tuesday

The second piece of good news is that Invest 96L behind Beryl is not expected to develop, at least not in the short term. Officially, it has a 20% chance of development over the next 7 days which is much lower than it was on Sunday. This makes sense because usually systems following another storm run into a hostile environment due to higher wind shear from the outflow of the leading storm. The leading storm usually causes the ocean to cool a bit in its wake so that helps as well. We shouldn't write it off altogether though. Several ensemble members show the system making another run at development once it reaches the western Caribbean or Gulf around Sunday or early next week, so that is something we need to watch. Right now it looks like anything that does develop will stay out of the northern Gulf, but it's possible that could change.

And now, the third piece of good news. It looks like once these two systems are out of the picture that the tropics will quiet down for several weeks as large scale conditions over the Atlantic basin become unfavorable for development. Right now this is only expected to last until the last week or week and a half of July but we'll see. Don't let the quiet period get your guard down as I'm concerned that the lull will just be priming the system for what could be a very busy August and September. So if you're keeping score, the good news is that we don't have a second Beryl roaring through the Caribbean and I think it's pretty likely that we will not see any impacts from tropical weather for the foreseeable future other than large waves and rip currents along the coast.

Here in the Southeast it is going to be typical July weather through the holiday weekend. In case you forgot, that means hot (ok, very hot) with a chance or rain on and off through the next week or so.

Happy Independence Day and stay safe.

Chris